A Level Physics Kinematics SUVAT equations Objectives Spec

A –Level Physics: Kinematics- SUVAT equations

Objectives: • Spec point 9: be able to use the equations for uniformly accelerated motion in one dimension using SUVAT equations • Spec point 15: understand how to make use of the independence of vertical and horizontal motion of a projectile moving freely under gravity Additional skills gained: • Advanced calculation • Component Isolation

Lesson-Link: The string of beads… https: //www. youtube. com/wat ch? v=n. DKGHGd. XLEg You have 10 mins to figure it out….

What is Kinematics? KINEMATICS Motion Scientific Study

What you’ll be able to calculate

From simple… What is the simplest equation you can think of that relates distance, speed and time? Convert this into a vector form You use this equation when there is NO ACCELERATION OCCURRING! Careful! Displacement is shown by an ‘s’ but it’s not representing speed!

To complex… So far, we have covered equations for constant motion but without acceleration. So how do we deal with motion with constant acceleration? . . SUVA T It’s an acronym! Write the word nice and big and using colours! For each one, annotate what it represents and the unit it is measured in!

Unravelling the maths… Don’t forget as we’re going through this that these equations only work with constant acceleration and that often the value for acceleration can be substituted for ‘g’ as gravitational force is commonly used in questions! SUVA T Task: We are soon going to start a flow chart of the equations! Start these on a new page with clear highlighting of the equations.

Step 1, equation 1 SUVA T Rearrange the equation for acceleration to have v as the subject

SUVA T Step 2, equation 2 If acceleration is constant then what is the average velocity of a journey between two points? Try combining this with the equation for non-acceleration displacement (s= v x t) a. k. a Average ‘v’

1 + 2 makes equation 3! SUVAT We need to combine the first and second equations. Let’s try first to do it by putting the first into the second… Work out the simplest form…

1 + 2 makes equation 3! SUVAT Work out the simplest form…

SUVAT 1 + 2 makes equation 4…as well… If we combine the equations again but this time changing equation 1 to be in the form of t….

What we haven’t got… SUVAT Make a table whereby you have all of the equations on the left hand side, and the quantity that is missing each time. If the SUVAT doesn’t contain the needed variable then don’t use it!

Worked Example A man drops a rock from the top of a cliff and the rock takes 3 second to reach the bottom. Calculate both the velocity it reaches before hitting the ground and the distance it fell 1. Pick the Equation: • Which equation contains the quantity we want and a quantity we know? We want: v We have: t • • Only two equations have both, and We can’t use the first one as it contains ‘s’ which we do not know yet! So we use the second! 2. Rearrange: • Rearrange the equation to make the needed quantity the subject. Luckily in this case we don’t need to! 3. Plug the values in: • We know that time here is 3 s, we know that the initial velocity was 0 ms-1 and acceleration must be 9. 81 ms-2.

Worked Example 4. A man drops a rock from the top of a cliff and the rock takes 3 second to reach the bottom. Calculate both the velocity it reaches before hitting the ground and the distance it fell Repeat for the other quantity: • Which equation contains the quantity we want and a quantity we know? We want: s We have: t and v • Two equations can be used here: and • Solving for ‘s’ gives us 44. 1 m! The key to SUVAT calculations is just to spend a little time working out the correct equation to use!

Practice Questions A bird drops a stone from 88 m above a pond, how long will it take the stone to hit the surface and what speed will it be travelling at just before it hits the water? An alien is holidaying on Pluto and throws a tennis ball vertically upward at a speed of 20 ms-1 causing it to reach the peak of its journey a whopping 303 m above the point of release. Calculate the acceleration due to gravity on Pluto

Extension/IS Write

Objectives: • Spec point 9: be able to use the equations for uniformly accelerated motion in one dimension using SUVAT equations • Spec point 15: understand how to make use of the independence of vertical and horizontal motion of a projectile moving freely under gravity Additional skills gained: • Advanced calculation • Component Isolation